赣江流域红层盆地典型构造样式与地下水动力学模式

    Typical structural geology and groundwater dynamics in red beds basins of Ganjiang River Basin, South China

    • 摘要: 中国陆相红层广泛分布,占陆地总面积的9.5%,大量城镇居民和农业种植区分布于不同区域的陆相红层盆地内,红层地区地下水资源普遍紧缺,干旱日趋严重,形势严峻,成为扶贫攻坚的重点。中国南方以赣江流域红层盆地为典型代表,红层主要分布于NE向展布的断陷盆地,其形成演化、空间分布和构造样式受NE向区域伸展断裂构造控制,红层内构造以NE向伸展断层和局部平缓褶皱为主要变形特征。盆地内红色砂砾岩层极差的分选性和完好的铁质胶结,使其具有低孔隙和低渗透特征,且厚度大分布广,成为红层盆地地下水贫瘠和补给效率低的主要原因。盆地内断裂构造及其伴生节理裂隙构成地下水的主要储存空间,也为地表水和地下水的交换提供运移和渗透通道。地下水的补给、红层内膏盐矿物及重金属元素的淋滤富集、地表农业和工业废水及污染物的下渗均受盆内断裂构造的控制。地下水的空间分布、资源量、补给效率和水质强烈受控于盆内局部变形构造,具有显著的非均一性。红层盆地内断裂构造的发育、活动性质及其伴生裂隙网络研究对地下水资源评价、动态监测和高效利用具有重要的科学指导意义。

       

      Abstract: Continental red-beds are widely distributed in China, accounting for 9.5% of the total land area.A large number of urban residents and agricultural planting areas are located in different continental red-bed basins.The groundwater resources in the red-beds area are generally in short supply, and the drought is becoming more and more serious, which has become the focus of poverty alleviation.The red-beds basins in Ganjiang River Basin are typical examples in South China.Red-beds layers are mainly distributed in NE trending fault basins.Their formation and evolution, spatial distribution and structural style are controlled by NE trending regional extensional faults.The deformation in red-beds basins are characterized by NE trending extensional faulting and local gentle folding.The poor separability and complete iron cementation of the thick red glutenite in the basin make them characterized by low porosity and low permeability, which are the main reasons for the lack of groundwater and low recharge efficiency in the red-beds basin.The faults and associated fractures in the basin provide the main storage space for groundwater and also provide migration and seepage channels for the exchange of surface water and groundwater.The recharge of groundwater, the leaching and enrichment of gypsum minerals and heavy metals in red-beds, and the infiltration of agricultural and industrial wastewater and pollutants are all controlled by the faults in the basin.The spatial distribution, resource quantity, recharge efficiency and quality of groundwater are strongly controlled by the local deformed structures in the basin and are characterized by significant heterogeneity.The development, activity and associated fracture network of faults in red-beds basin have important significance for groundwater resource evaluation, dynamic monitoring and efficient utilization.

       

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